The present invention relates to digital rights management and signing electronic documents.
A digital signature, like a conventional handwritten signature, identifies a person or entity signing a document. Digital signatures allow a person to attest to something about a document by signing their name to it. Thus, for example, digital signatures can be used to authenticate and safeguard information by allowing authors and others to “sign” electronic documents with a unique electronic signature that identifies the person who applied it as having read, reviewed, or contributed to the document's creation. A digital signature can also verify that a document has not been altered since it was sent.
Key-based signatures encode an electronic document with an encrypted unique signature that positively identifies the person who applied the signature, when it was signed, and other user-determined information. Key-based systems can also control access to a document, allowing only certain persons holding certain keys to read or modify the document. In some applications, a digital signature in a document is bound to that document in such a way that repurposing the signed document—for example, altering the signed document or moving the signature to a different document—invalidates the signature.